Traditional incandescent lamps are currently being replaced by more energy efficient solid state based alternatives, such as light emitting diode (LED) based lighting devices. LEDs, as well as electronics for driving the LEDs, generate heat during operation of the lighting device. However, high temperatures shorten the lifetime of the LEDs. In design of LED-based lighting devices, the thermal issue is considered to be a bottleneck that restricts optical output and lifetime of the lighting device. Some lighting devices comprise a structure able to generate a chimney effect within the lighting device in order to enhance heat dissipation from the LEDs. The chimney effect is utilized to create an air flow in the lighting device for cooling the LEDs by means of convection. An example of such a lighting device is shown in US2008/0285271.